Controller for variable transmission

ABSTRACT

An electronic controller for a variable ratio transmission and an electronically controllable variable ratio transmission including a variator or other CVT are described herein. The electronic controller can be configured to receive input signals indicative of parameters associated with an engine coupled to the transmission. The electronic controller can also receive one or more control inputs. The electronic controller can determine an active range and an active variator mode based on the input signals and control inputs. The electronic controller can control a final drive ratio of the variable ratio transmission by controlling one or more electronic solenoids that control the ratios of one or more portions of the variable ratio transmission.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/160,624, filed Oct. 15, 2018, entitled “CONTROLLER FOR VARIABLETRANSMISSION,” scheduled to issue on Sep. 21, 2021 as U.S. Pat. No.11,125,329, which is a continuation of U.S. patent application Ser. No.14/529,773, filed Oct. 31, 2014, entitled “CONTROLLER FOR VARIABLETRANSMISSION,” and issued as U.S. Pat. No. 10,100,927, which is adivisional of U.S. patent application Ser. No. 12/271,611, filed Nov.14, 2008, entitled “CONTROLLER FOR VARIABLE TRANSMISSION,” and issued asU.S. Pat. No. 8,996,263, which claims the benefit of U.S. ProvisionalApplication No. 60/988,560, filed Nov. 16, 2007, and entitled“CONTROLLER FOR A CONTINUOUSLY VARIABLE TRANSMISSION.” The disclosuresof all of the above-referenced prior applications, publications, andpatents are considered part of the disclosure of this application, andare incorporated by reference herein in their entirety.

BACKGROUND

Continuously variable transmissions (CVT) and transmissions that aresubstantially continuously variable are increasingly gaining acceptancein various applications. The process of controlling the ratio providedby the CVT is complicated by the continuously variable or minutegradations in ratio presented by the CVT. Furthermore, the range ofratios that may be implemented in a CVT may not be sufficient for someapplications. A transmission may implement a combination of a CVT withone or more additional CVT stages, one or more fixed ratio rangesplitters, or some combination thereof in order to extend the range ofavailable ratios. The combination of a CVT with one or more additionalstages further complicates the ratio control process, as thetransmission may have multiple configurations that achieve the samefinal drive ratio.

The different transmission configurations can, for example, multiplyinput torque across the different transmission stages in differentmanners to achieve the same final drive ratio. However, someconfigurations provide more flexibility or better efficiency than otherconfigurations providing the same final drive ratio.

The criteria for optimizing transmission control may be different fordifferent applications of the same transmission. For example, thecriteria for optimizing control of a transmission for fuel efficiencymay differ based on the type of prime mover applying input torque to thetransmission. Furthermore, for a given transmission and prime moverpair, the criteria for optimizing control of the transmission may differdepending on whether fuel efficiency or performance is being optimized.

Systems and methods are described herein for addressing the complicatedand sometimes competing criteria that are addressed in controlling atransmission final drive ratio.

SUMMARY

An electronic controller for a variable ratio transmission and anelectronically controllable variable ratio transmission including avariator or other CVT are described herein The electronic controller canbe configured to receive input signals indicative of parametersassociated with an engine coupled to the transmission. The electroniccontroller can also receive one or more control inputs. The electroniccontroller can determine an active range and an active variator modebased on the input signals and control inputs. The electronic controllercan control a final drive ratio of the variable ratio transmission bycontrolling one or more electronic solenoids that control the ratios ofone or more portions of the variable ratio transmission.

Aspects of the invention include a method of controlling a variableratio transmission. The method includes receiving a plurality of inputsignals, determining an active control range from a plurality of controlranges based at least in part on the plurality of input signals,determining an active variator mode from a plurality of variator modesbased on the plurality of input signals and the active control range,and controlling an operation of the variator based on the input signalsand the active variator mode.

Aspects of the invention include a method of controlling a variableratio transmission. The method includes receiving one or more electronicinput values, and controlling a current applied to a control solenoid tovary a position of a variator control piston that operates to vary aratio provided by a variator by varying an angle of a rotation axis forat least one rotating planet in the variator.

Aspects of the invention include a controller system that includes ashift schedule module configured to store a shift schedule map, a shiftpoint module coupled to the shift schedule module, configured to receivea plurality of electronic input signals, and configured to determine anactive control range from a plurality of control ranges based at leastin part on the plurality of electronic input signals and the shiftschedule map, a variator mode module configured to determine a variatormode based on the plurality of electronic input signals and the activecontrol range, and a control module configured to control a ratio of avariator based on the variator mode.

Aspects of the invention include a controller system that includes atransmission having a variable ratio variator whose ratio is variedbased at least in part on a position of a longitudinal axis of at leastone rotating planet within the variator, and an electronic controllerconfigured to receive a plurality of inputs and generate a controloutput that varies the position of a longitudinal axis of the at leastone rotating planet within the variator based on the plurality ofinputs.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, objects, and advantages of embodiments of the disclosurewill become more apparent from the detailed description set forth belowwhen taken in conjunction with the drawings, in which like elements bearlike reference numerals.

FIG. 1 is a simplified functional block diagram of a drive apparatusincluding a variable ratio transmission.

FIG. 2 is a simplified power flow diagram of an embodiment of a variableratio transmission with electronic control.

FIG. 3A is a simplified diagram of a variable ratio transmission havingelectronic control.

FIG. 3B is a simplified diagram of an embodiment of a variator.

FIG. 3C is a simplified fluid flow diagram of an embodiment of avariable ratio transmission.

FIG. 4 is a simplified functional block diagram of an embodiment of anelectronic controller for a variable ratio transmission.

FIG. 5 is a simplified diagram of an embodiment of a transmission shiftcurve implemented by an electronic controller.

FIG. 6 is a simplified diagram of an embodiment of an engine speed mapimplemented by an electronic controller.

FIG. 7 is a simplified diagram of an embodiment of a variator mapimplemented by an electronic controller.

FIG. 8 is a simplified diagram of an embodiment of a variator mapimplemented by an electronic controller.

FIG. 9 is a simplified diagram of an embodiment of an engine speed limitmap implemented by an electronic controller.

FIG. 10 is a simplified diagram of an embodiment of a variator ratelimit map implemented by an electronic controller.

FIG. 11 is a simplified diagram mapping estimated engine torque tothrottle position.

FIG. 12 is a simplified diagram of an embodiment of a line pressureschedule.

FIG. 13 is a simplified diagram of an embodiment of a line pressurecontrol map.

FIG. 14 is a simplified diagram of an embodiment of a clutch applicationprofile.

FIG. 15 is a simplified diagram of an embodiment of a clutch pressurecontrol map.

FIG. 16 is a simplified diagram of an embodiment of a torque converterclutch curve.

FIG. 17 is a simplified flow chart of an embodiment of a method ofcontrolling a variable ratio transmission.

FIG. 18 is a simplified flowchart of an embodiment of a method ofcontrolling a variator in a variable ratio transmission.

FIG. 19 is a schematic diagram of an embodiment of a fluid flow diagramof an embodiment of a valve system that can be implemented on a variableratio transmission.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

An electronic controller for a variable ratio transmission is describedherein that enables electronic control over a variable ratiotransmission having a continuously variable ratio portion, such as aContinuously Variable Transmission (CVT), Infinitely VariableTransmission (IVT), or variator. The electronic controller can beconfigured to receive input signals indicative of parameters associatedwith an engine coupled to the transmission. The parameters can includethrottle position sensor values, vehicle speed, gear selector position,user selectable mode configurations, and the like, or some combinationthereof. The electronic controller can also receive one or more controlinputs. The electronic controller can determine an active range and anactive variator mode based on the input signals and control inputs. Theelectronic controller can control a final drive ratio of the variableratio transmission by controlling one or more electronic solenoids thatcontrol the ratios of one or more portions of the variable ratiotransmission.

The electronic controller described herein is described in the contextof a continuous variable transmission, such as the continuous variabletransmission of the type described in International Application NumberPCT/US2008/053347, entitled “CONTINUOUSLY VARIABLE TRANSMISSIONS ANDMETHODS THEREFOR,” assigned to the assignee of the present applicationand hereby incorporated by reference herein in its entirety. However,the electronic controller is not limited to controlling a particulartype of transmission but can be configured to control any of severaltypes of variable ratio transmissions.

As used herein, the terms “operationally connected,” “operationallycoupled”, “operationally linked”, “operably connected”, “operablycoupled”, “operably linked,” and like terms, refer to a relationship(mechanical, linkage, coupling, etc.) between elements whereby operationof one element results in a corresponding, following, or simultaneousoperation or actuation of a second element. It is noted that in usingsaid terms to describe the various embodiments, specific structures ormechanisms that link or couple the elements are typically described.However, unless otherwise specifically stated, when one of said terms isused, the term indicates that the actual linkage or coupling may take avariety of forms, which in certain instances will be obvious to a personof ordinary skill in the relevant technology.

The term “radial” is used herein to indicate a direction or positionthat is perpendicular relative to a longitudinal axis of a transmissionor variator. The term “axial” as used herein refers to a direction orposition along an axis that is parallel to a main or longitudinal axisof a transmission or variator. For clarity and conciseness, at timessimilar components labeled similarly (for example, control piston 582Aand control piston 582B) will be referred to collectively by a singlelabel (for example, control pistons 582).

FIG. 1 is a simplified functional block diagram of an embodiment of adrive apparatus 100, which is referred to herein as the drive 100. Insome embodiments, the drive 100 includes a transmission 101operationally coupled between a prime mover 102 and a load 114. Theprime mover 102 delivers power to the transmission 101, and thetransmission 101 delivers power to the load 114. The prime mover 102 canbe one or more of any number of power generating devices, and the load114 can be one or more of any number of driven devices or components.Examples of the prime mover 102 include, but are not limited to,engines, including but not limited to internal combustion engines andexternal combustion engines, motors, such as electric motors, and thelike, or some combination thereof. Examples of loads include, but arenot limited to, drive train differential assemblies, power take-offassemblies, generator assemblies, pump assemblies, and the like.

In one embodiment, the transmission 101 includes an input interface 104,a variator 106, an output interface 110, and a range box 112. The inputinterface 104 is operationally coupled to the prime mover 102. Thevariator 106 can be operationally coupled between the input interface104 and the output interface 110. The range box 112 is operationallycoupled between the output interface 110 and the load 114.

A controller 108, such as an electronic controller, can be configured tomonitor one or more states, properties, or characteristics of the drive100. The controller 108 can be configured to receive one or more inputsfrom a user interface 107, which is typically local to the drive 100 andcontroller 108. The controller 108 may optionally include a remoteinterface 109 that is configured to receive one or more inputs from aremote controller (not shown).

The controller 108 can be coupled to the prime mover 102 and can beconfigured to monitor or otherwise determine one or more characteristicsof the prime mover 102. In a particular embodiment where the prime mover102 includes an internal combustion engine, the controller can beconfigured to monitor, for example, a throttle position, an enginespeed, and the like or some combination thereof.

The controller 108 can also be coupled to one or more stages within thetransmission 101, and can be configured to monitor or otherwisedetermine one or more characteristics of the transmission 101. Forexample, the controller 108 can be configured to monitor or otherwisedetermine various mechanical characteristics, fluid pressures andtemperatures within each of the input interface 104, variator 106,output interface 110, and range box 112.

The controller 108 can be coupled to the user interface 107 to receiveor monitor inputs provided locally. The user interface 107 can include,for example, a gear shift controller, typically referred to as a gearshift lever. The user interface 107 may also include one or more manualmode selectors, which can be selectively activated to control anoperational mode of the drive 100. The manual mode selectors can be, forexample, one or more switches or programmable elements. In an particularexample, the manual mode selectors can selectively indicate an economymode, a performance mode, a luxury mode, and the like. The manual modeselectors need not be mutually exclusive, but may be activated ordisabled simultaneously or otherwise concurrently.

The controller 108 can be coupled to the remote controller (not shown)via the remote interface 109 and can be configured to receive one ormore inputs from the remote controller. The remote interface 109 can bea wired interface, wireless interface, and the like, or some combinationthereof. In one embodiment, the remote interface 109 can support a wiredcommunication standard. In another embodiment, the remote interface 109can support a wireless communication standard. In other embodiments, theremote interface 109 can support a proprietary wired or wirelesscommunication interface. Alternatively, the remote interface 109 can beconfigured to support a combination of wired and wireless interfaces.

The controller 108 can receive, from the remote controller via theremote interface 109, one or more control inputs or monitor inputs. Thecontroller 108 can be configured, for example, to receive programmableupdates, tables, operational maps, other information, and the like, orsome combination thereof from the remote controller.

The controller 108 can be configured to provide one or more outputs,based at least in part on the inputs, and which can be used to controloperational characteristics of the drive 100. For example, thecontroller 10 can control operational characteristics of the drive 100,and in particular the transmission 101, based on a combination of theinputs and one or more predetermined operational maps, algorithms, orprocesses. The controller 108 can also be configured to provide one ormore outputs that communicate or otherwise indicate a state,characteristic, or condition of one or more aspects of the drive 100.For example, the controller 108 can be configured to control one or moreindicators in the user interface 107 or provide diagnostic informationto the remote controller via the remote interface 109.

As will be described in greater detail below, the controller 108 can beconfigured to control a final drive ratio of the transmission 101,including the drive ratio provided by the variator 106 and the driveratio enabled of the range box 112. The controller 108 can also beconfigured to control operational characteristics such as shiftingcharacteristics.

In one embodiment the controller 108 can be configured to control aplurality of solenoid valves (not shown) that can control aspects ofeach of the input interface 104, variator 106, and range box 112. Thecontroller 108 can be configured to control one or more of the solenoidvalves using open loop control. Alternatively, or additionally, thecontroller 108 can be configured to control one or more of the solenoidvalves in a closed control loop that utilizes feedback informationprovided to or monitored by one or more inputs to the controller 108.

The input interface 104 can be configured for receiving power from theprime mover 102 and transferring such power to the variator 106. Theoutput interface 110 can be configured for combining power (that is,torque applied at a given rotational speed) from the variator 106 andtransferring such combined power to the range box 112. It is disclosedherein that neither the input interface 104 nor the output interface 110is necessarily limited to a particular respective physical and/oroperational configuration. Accordingly, the input interface 104 mayinclude any gearing or coupling structure suitable for providing suchdistributed power transfer and distribution functionality, and theoutput interface 110 may include any gearing or coupling structuresuitable for providing such combined power transfer functionality.Examples of the input interface 104 include, but are not limited to, atorque converter assembly, a hydraulic clutch coupling, a manuallyactuated clutch assembly, a computer-controlled clutch assembly, amagnetorheological clutch coupling, and the like, or some combinationthereof.

The variator 106 can be configured for enabling power distributedthereto from the input interface 104 to be transferred to the outputinterface 110 in a manner whereby torque and/or rotational speedassociated with that power is selectively variable (that is, selectivelyadjustable).

The range box 112 provides various gear selection and clutch engagementfunctionalities and operates to extend the range of final drive ratiosavailable from the transmission 101. Examples of such gear selectionfunctionality include, but are not limited to, selective engagement ofavailable range box gear ratios and selective engagement of various loaddrive directions. Examples of such clutch engagement functionalityinclude, but are not limited to, passive implementation of variousclutch engagement operations and active implementation of various clutchengagement operations.

FIG. 2 is a simplified diagram of a variable ratio transmission 101having electronic control. The variable ratio transmission 101 of FIG. 2can be, for example, the transmission implemented in the driveembodiment illustrated in FIG. 1.

The transmission 101 consists of four major subsystems. The subsystemsinclude a torque converter 210 with a lockup clutch 212, a variator 220,alternatively referred to as a CVT element, a power combiner 230, whichcan be implemented as a combining planetary gearset, and a two-speedrange box 240. The two speed range box 240 can be implemented, forexample, as a Ravigneaux gearset and clutches 242, 244, and 246. Thetransmission 101 is illustrated with a two speed range box 240 forpurposes of clarity. Other embodiments may omit the range box 240 andassociated clutches 242, 244, and 246 in favor of a reverser, whilestill other embodiments may implement more than one range box 240 or arange box 240 capable of more than two speeds.

The overall transmission ratio is determined by the torque converter210, the variator 220, and the range box 240. The range of ratiossupported by the variator 220 may produce an overlap in the range ofratios supported by the transmission 101 in the two different range box240 configurations. Thus, there are multiple ways to achieve a givenoverall ratio that occurs in the region of overlapping ranges.

An embodiment of a strategy chosen by the control system, and inparticular the controller 108, to perform the ratio selection andcontrol is described herein. In general, the variator 220 is relied uponfor more precise engine control and smoother operation at low vehiclespeeds.

The transmission controller 108 accepts inputs from one or more systemsensors and a driver, and operates one or more hydraulic solenoid valves243, 245, 247, 213, and 221, to control the range clutches 242, 244,246, variator 220 and torque converter clutch (TCC) 212. The controller108 can be configured to apply and release each of the solenoid valves213, 221, 243, 245, and 247 independently based at least in part on theone or more sensor inputs.

FIG. 3A is a simplified diagram of a variable ratio transmission 101having electronic control. In one embodiment, the transmission 101 caninclude a torque converter subassembly 800, a main shaft 1000, avariator 1200, a combining device 1400, a range box 1600, and atransmission housing 1800. The transmission housing 1800 can include abell housing 1810 (that is, a first housing portion) and a rear housing1820 (that is, a second housing portion) separably connected to the bellhousing 1810. In the embodiment illustrated, the torque convertersubassembly 800, the main shaft 1000, the variator 1200, the combiningdevice 1400, and the range box 1600 are operably mounted on or withinthe transmission housing 1800 in an axially aligned manner. Thus, it isdisclosed herein that the transmission housing 1800 is configured forhousing and supporting various subassemblies and/or components of thetransmission 101. In other embodiments, any one of the torque convertersubassembly 800, the variator 1200, the combining device 1400, and therange box 1600 can be arranged in a parallel shaft configurationrelative to the other components.

In some embodiments, the variator 1200 and the main shaft 1000 can beoperably coupled between a power output portion of the torque convertersubassembly 800 and power input portions of the combining device 1400.In operation, the torque converter subassembly 800 transfers power tothe variator 1200 through the main shaft 1000. The variator 1200supplies power to a first power input portion 1410 of the combiningdevice 1400. The main shaft 1000 supplies power to a second power inputportion 1405 of the combining device 1400. Power from the variator 1200and the main shaft 1000 can be supplied to the combining device 1400 ina selectively variable ratio (for example, power from the variator 1200in relation to power from the main shaft 1000) and can be combined bythe combining device 1400. The combining device 1400 delivers thecombined power to the range box 1600 via a power output portion 1401 ofthe combining device 1400. The power output portion 1401 can include acarrier of planetary gear set and/or a transfer shaft.

In one embodiment, the variator 1200 mounts on the main shaft 1000. Inone configuration, the variator 1200 and the main shaft 1000 form atorque split unit. More specifically, the ratio of torque transferred tothe combining device 1400 through the variator 1200 or through the mainshaft 1000 is selectively variable dependent upon a torque ratio settingof the variator 1200. To this end, the variator 1200 transfers power tothe combining device 1400 in a manner whereby the torque and/or therotational speed associated with that power is selectively andcontinuously variable (that is, adjustable). Thus, the variator 1200 canbe configured for receiving power of a first specification (for example,first torque and first rotational shaft speed) and outputting power of asecond specification (for example, second torque and second rotationalshaft speed).

The torque converter subassembly 800 is one embodiment of an inputinterface 104, for example, thereby providing the functionality oftransferring power from a prime mover attached to the torque convertersubassembly 800 to the variator 1200 via, for example, the main shaft1000. In other embodiments, a different type of input interface such as,for example, a manually controlled clutch subassembly, a computercontrolled clutch assembly, or a flywheel can be implemented in place ofthe torque converter subassembly 800. The combining device 1400 is anembodiment of an output interface, thereby providing the functionalityof combining power received from the variator 1200 and the main shaft1000 and transferring such power to the range box 1600. In oneembodiment, the range box 1600 receives power from the combining device1400 and outputs power in conjunction with providing one or more of thevarious gear selection and clutch engagement functionalities discussedabove in reference to FIG. 1. As is discussed further below, the rangebox 1600 in combination with the variator 1200 enables the transmission101 to operate in multiple modes (that is, a multi-mode transmission).

In one embodiment, the variator 1200 can include an inputload-cam-and-traction-ring subassembly 2000A, an outputload-cam-and-traction-ring subassembly 2000B, an array ofplanet-and-shift-lever subassemblies 2100, a shift-cam-and-sunsubassembly 2200, and a stator-manifold subassembly 2300. In oneembodiment, the shift-cam-and-sun subassembly 2200 is supported by thestator-manifold subassembly 2300. The shift-cam-and-sun subassembly 2200is supported in a manner enabling the shift-cam-and-sun subassembly 2200to be translated along a longitudinal axis LA1 of the main shaft 1000.The planet-and-shift-lever subassemblies 2100 are arrayed angularlyaround the main shaft 1000, and are supported jointly by theshift-cam-and-sun subassembly 2200 and the stator-manifold subassembly2300. Each one of the planet-and-shift-lever subassemblies 2100 issupported in a manner that facilitates synchronous rotation of all theplanet-and-shift-lever subassemblies 2100 about a respective referenceaxis TA1 extending through a planet 2102 of each one of theplanet-and-shift-lever subassemblies 2100. Through such synchronousrotation, all of the planet-and-shift-lever subassemblies 2100 are inthe same relative rotational position at a given point in time. The axisTA1 associated with each one of the planet-and-shift-lever subassemblies2100 extends through a center point of the respective planet 2102substantially perpendicular to a radial reference axis RA1 extendingfrom the longitudinal axis LA1 through the center point of therespective planet 2102.

In some embodiments, the main shaft 1000 includes a first end portion1005, a central portion 1010 and a second end portion 1015. The firstend portion 1005 couples to a power output portion 805 of the torqueconverter assembly 800 (for example, an output hub of a converterturbine) in a manner precluding relative rotation of the main shaft 1000with respect to the power output portion 805. The central portion 1010of the main shaft 1000 couples to the input load-cam- and -traction-ringsubassembly 2000A in a manner precluding relative rotation of the mainshaft 1000 with respect to the input load-cam-and-traction-ringsubassembly 2000A. The second end portion 1015 of the main shaft 1000couples to the first power input portion 1405 of the combining device1400 in a manner precluding relative rotation of the main shaft 1000with respect to the first power input portion 1405. The outputload-cam-and-traction-ring subassembly 2000B of the variator 1200couples to a first power input portion 1410 of the combining device 1400in a manner precluding relative rotation of the outputload-cam-and-traction-ring subassembly 2000B with respect to the firstpower input portion 1410. Thus, the main shaft 1000 is suitablyconfigured for transferring power from the torque converter subassembly800 (a) directly to the combining device 1400, and (b) to the combiningdevice 1400 through the variator 1200.

Each of the planets 2102 is located by the inputload-cam-and-traction-ring subassembly 2000A, the outputload-cam-and-traction-ring subassembly 2000B, and the shift-cam-and-sunsubassembly 2200. The main shaft 1000 can be configured to exert torqueon the input load-cam-and-traction-ring subassembly 2000A. Throughtraction at a respective input traction interface TI1 between the inputload-cam-and-traction-ring subassembly 2000A and each planet 2102,torque is exerted by the input load-cam-and-traction-ring subassembly2000A on the planets 2102, thereby causing each planet 2102 to rotateabout a respective planet axle 2104. The input traction interface TI1 isdefined, as used here, at a region of contact between the inputload-cam-and -traction-ring subassembly 2000A and the respective planet2102. Preferably, but not necessarily, traction at each input tractioninterface TI1 and each output traction interface TI2 is provided throughan elastohydrodynamic layer formed by a traction fluid.

Through traction at a respective output traction interface T12 betweenthe input load-cam-and-traction-ring subassembly 2000B and each planet2102, torque is exerted by the planets 2102 on the output load-cam- and-traction-ring subassembly 2000B, thereby causing the outputload-cam-and-traction-ring subassembly 2000B to rotate about the mainshaft 1000. The output traction interface T12 is defined, as used here,at a region of contact between the output load-cam- and -traction-ringsubassembly 2000B and the respective planet 2102. As shown in FIG. 3A,the output load-cam- and -traction-ring subassembly 2000B can be coupledto the combining device 1400. Accordingly, torque can be transferredfrom the main shaft 1000 to the combining device 1400 through thevariator 1200.

As discussed above in reference to FIG. 3A, the ratio of torquetransferred to the combining device 1400 through the variator 1200 orthrough the main shaft 1000 can be selectively variable dependent uponthe torque ratio of the variator 1200. The torque ratio refers to arelative position of the input traction interface TI1 and the outputtraction interface T12, relative to the axis LA2, for a given tilt ofthe planet-and-shift-lever subassemblies 2100. When the tangentialsurface velocity of the planets 2102 at the input traction interface TI1is the same as the tangential surface velocity of the planets 2102 atthe output traction interface T12, the torque ratio is substantiallyequal to 1 and there is no corresponding torque multiplication. Throughtilting of the planet-and-shift-lever subassemblies 2100, the ratio ofthe tangential surface velocity of the planets 2102 at the inputtraction interface TI1 to that of the tangential surface velocity of theplanets 2102 at the output traction interface T12 is selectivelyadjustable. As discussed further below, the shift-cam- and -sunsubassembly can be configured such that translation of the shift-cam-and-sun subassembly 2200 causes such tilt of the planet-and-shift-leversubassemblies 2100. The direction of tilt of the planet-and-shift-leversubassemblies 2100 from the position corresponding to the torque ratioof 1 dictates whether the torque multiplication is greater than 1 (thatis, torque output is greater than torque input) or less than 1 (that is,torque input is greater than torque output).

As depicted in FIG. 3A, the input traction interface TI1 and the outputtraction interface T12 are angularly equidistant relative to a radialreference axis RA1 extending through the tangential reference axis TA1.As a result, the torque ratio is 1 when a longitudinal axis LA2 of eachplanet 2102 is parallel with the longitudinal axis LA1 of the main shaft1000. Such an equidistant configuration provides for a balancedadjustment range such that full adjustment of the planet-and-shift-leversubassemblies 2100 in a first adjustment direction results in the sameabsolute torque multiplication value as full adjustment in a seconddirection. In other embodiments, the input traction interface TI1 andthe output traction interface TI2 may be non-equidistant from thereference axis TA1 when the torque ratio is 1.0 and the longitudinalaxis LA2 is parallel with the longitudinal axis LA1. Such anon-equidistant configuration provides for biasing of the adjustmentrange such that full adjustment of the planet-and-shift-leversubassemblies 2100 in the first adjustment direction results in adifferent absolute torque multiplication value than full adjustment inthe second adjustment direction.

As illustrated in the embodiment of FIG. 3A, the variator 1200 can beaxially constrained on the main shaft 1000 between an axial reactionflange 1020 of the main shaft 1000 and an axial lock nut 1305. The axiallock nut 1305 includes a threaded bore configured for mating with acorresponding threaded portion 1025 of the main shaft 1000. The axialreaction flange 1020 can be fixedly attached to the main shaft 1000adjacent the second end portion 1015 of the main shaft 1000. Thethreaded portion 1025 can be an integral component of the main shaft1000, adjacent to the central portion 1010 of the main shaft 1000. Inone embodiment, the main shaft 1000 includes an anti-rock pilotingsurface 1028 configured for engaging a mating anti-rock piloting surfaceof the axial lock nut 1305 for limiting rocking of the axial lock nut1305 with respect to the main shaft 1000.

A first engagement extension 1030 at the first end portion 1005 of themain shaft 1000 can be configured for engaging or supporting a bearingassembly 810 that interfaces with certain components of the torqueconverter subassembly 800 or other support member. A second engagementextension 1035 at the second end portion 1015 of the main shaft 1000 canbe configured for engaging or supporting a bearing assembly 1415 thatinterfaces with certain components of the combining device 1400. In someembodiments, the bearing assemblies 810, 1415 include each only abushing or a bearing component. In other embodiments, the bearingassemblies 810, 1415 each include a bushing or a bearing component and aseal component configured to engage a mating surface of the respectiveengagement extension 1030, 1035.

FIG. 3B is a simplified diagram of an embodiment of a variator 1200 thatcan be, for example, the variator in the transmission of FIG. 3A. In theillustrated embodiment of the variator 1200, each one of theplanet-and-shift-lever subassemblies 2100 includes a planet 2102rotatably mounted on a planet axle 2104, which can be positioned on aplanet central bore 2103. Spaced apart planet bearings 2108, an innerspacer 2110, and outer spacers 2112 can mount coaxially on the planetaxle 2104. In some embodiment, the inner spacer 2110 is positionedbetween the planet bearings 2108, and each one of the planet bearings2108 is positioned between a respective one of the outer spacers 2112and the inner spacer 2110. Accordingly, each planet 2102 is rotatablymounted on a respective planet axle 2104 in a load-bearing and rotatablemanner. The variator 1200 is not limited to a particular planet bearingand spacer arrangement for rotatably mounting each planet 2102 on therespective planet axle 2104. For example, in some embodiments, a planetbearing and spacer arrangement using more than two or less two planetbearings and more than two or less spacers (that is, inner positionand/or outer position) can be implemented.

Planet axle shift levers 2106 (“shift levers 2106”) can be fixedlyattached to opposing end portions 2107 of the planet axle 2104 such thatthe planet 2102 is positioned between the shift levers 2106. The planetaxle 2104 extends through a planet axle bore 2111 of each shift lever2106. In one embodiment, the opposing end portions 2107 include skewroller shoulders 2109 on which skew rollers 2122 mount. Each skew roller2122 can be held in place by a washer 2124 and a clip ring 2126, whichclip ring 2126 can be engaged within a groove in the skew rollershoulder 2109. It is disclosed herein that, in some embodiments, a shiftlever 2106 can include one or more features (not shown) such as, forexample, a recess, a channel, etc., for providing clearance with othercomponents of the variator 1200.

In some embodiments, a shift guide roller axle 2116 can be engagedwithin a shift guide roller axle bore 2117 of each shift lever 2106 andwithin a corresponding axle capturing feature 2119 of the planet axle2104. In one embodiment, the shift guide roller axle bore 2117intersects and is generally perpendicular to the planet axle bore 2111.The shift guide roller axle bore 2117 is adjacent to a first end portion2121 of the shift lever 2106. Examples of the axle capturing feature2119 include, but are not limited to, a feature generally characterizedas a notch, a cut out, a channel, a seat, or the like. The shift guideroller axle 2116 and the corresponding axle capturing feature 2119 canbe configured for limiting (for example, substantially precluding)radial displacement of the shift guide roller axle 2116 with respect tothe engaged axle capturing feature 2119. Thus, such mating configurationof the shift guide roller axle 2116 and the corresponding axle capturingfeature 2119 limits displacement of the shift lever 2106 along thelongitudinal axis LA2 of the planet axle 2104 when the shift guideroller axle 2116 is mounted on the planet axle 2104 with the shift guideroller axle 2116 engaged within the shift guide roller axle bore 2117and the corresponding axle capturing feature 2119. Shift guide rollers2114 can be mounted on opposing end portions of each shift guide rolleraxle 2116. Each shift guide roller axle 2116 can be secured in place by,for example, washers 2118 and clip rings 2120, which clip rings 2120 canbe engaged within a groove 2191 of the shift guide roller axle 2116. Inother embodiments, the shift guide roller axle 2116 can be secured by,for example, an interference fit, press fit, etc. Side faces 2244 can beconfigured to substantially constrain movement of the shift lever 2106,thereby limiting rotation of the respective shift lever 2106 about thelongitudinal axis LA1 of the variator 1200.

In an embodiment of the variator 1200, the shift-cam-and-sun subassembly2200 can include sun 2202, bearings 2204, shift cams 2206, controlpistons 2208, piston tube 2210, shim 2212, inner seals 2214, and outerseals 2216. As shown in FIG. 3C, in some embodiments, the controlpistons 2208 are coupled to the shift cams 2206 through the piston tube2210. The control pistons 2208 and the shift cams 2206 can be mounted onthe piston tube 2210 by, for example, a press-fit interface. The sun2202 can be operationally coupled to the shift cams 2206 through thebearings 2204. The bearings 2204 can be configured to transfer axial andradial loads between the sun 2202 and the shift cams 2206. The sun 2202and the shift cams 2206 can be configured to receive the bearings 2204.The variator 1200 is not limited to bearings of a particular type. Forexample, an angular contact bearing is a suitable bearing type for thebearings 2204.

The position of the control pistons 2208 can be selectably controlled,for example, via an electronic solenoid under the control of anelectronic controller. The controller can utilize a closed loop controlto monitor the transmission state and adjust the electronic solenoid,and thereby the position of the control pistons 2208, accordingly.

FIG. 3C is a simplified fluid flow diagram 300 of an embodiment of avariable ratio transmission. The fluid flow diagram 300 can illustrate,for example, a fluid flow within the transmission of FIG. 3A. The fluidflow diagram 300 illustrates schematically the control of fluid flow andfluid pressures through the use of one or more electronic solenoids. Thefluid flow and controls illustrated in the flow diagram 300 of FIG. 3Care illustrative and not intended to be limiting on the number and typeof controls that may be implemented within a transmission. Although thefluid flow diagram generally illustrates the electronic solenoids, e.g.213, as controlling a fluid exhaust, the electronic solenoids are notlimited to controlling fluid exhaust, and may be configured to controlinlet fluid flow or a chamber volume in order to effectuate the desiredcontrol.

In the example of FIG. 3C, fluid, such as hydraulic fluid within thetransmission is contained within a sump 350. A pump 310 draws the fluidfrom the sump, pressurizes it, and distributes it to one or more controlpaths within the transmission. The pump 310 can be, for example, drivenby the primary move via the input interface. In one example, an internalcombustion engine drives the torque converter, and the torque converterdrives the pump 310. The pump 310 typically includes one or moremechanisms (not shown) for controlling, regulating, or otherwiselimiting the fluid pressure. Such mechanisms include, but are notlimited to solenoids, check balls, diaphragms, regulators, and the like,or some combination thereof. The line pressure can be static or may bedynamically regulated by the controller. The pressure regulator is notillustrated for the sake of clarity.

The pressurized fluid from the pump 310 is distributed along a pluralityof control passages. Each of the control passages can be sized tominimize the drop in fluid pressure experienced at the output of thepump 310 across the entire control range of flow in the control passage.

A first control passage can be, for example, coupled to the torqueconverter and operate to control the engagement and disengagement of thetorque converter clutch. A first electronic solenoid 213 under thecontrol of the controller can selectively control a torque converterclutch piston 312 to selectively control the pressure applied to thetorque converter clutch. For example, the first electronic solenoid 213can be substantially de-energized when the torque converter clutch isnot engaged, where de-energized refers to the currently flowing throughthe solenoid that is insignificant relative to an actuation current. Thefluid supplied in the first control passage is permitted to exhaust backto the sump 350 thereby inhibiting sufficient pressure to actuate thetorque converter clutch. The first electronic solenoid 213 can beengaged to substantially limit fluid exhaust from the first controlpassage, thereby permitting build up of pressure within the firstcontrol passage and engaging the torque converter clutch.

A second control passage may be implemented in conjunction with a secondelectronic solenoid 221 and variator control piston 320 to control theratio provided by the variator. The controller can control the amount ofcurrent to the second electronic solenoid 221 to control the fluidexhaust through the second control passage and thereby the position ofthe variator control piston 320. The position of the variator controlpiston 320, as described above in relation to FIG. 3B, controls theshift-cam-and-sun subassembly and planet-and-shift-lever subassemblies,which control the ratio provided by the variator.

A third control passage may be implemented in conjunction with a thirdelectronic solenoid 243 and range clutch control piston 342 to controlthe engagement of the range clutch. The controller can provide anactuation current to the third electronic solenoid 243 to engage therange clutch control piston 342 and permit fluid pressure to engage theclutch. Conversely, the controller can inhibit current to the thirdelectronic solenoid 243 to disengage the range clutch control piston 342and permit fluid in the third control passage to exhaust to the sump350, thereby inhibiting pressure applied to the range clutch. Theposition of the range clutch can be used to control the ratio of therange box.

Similarly, a fourth control passage may be implemented in conjunctionwith a fourth electronic solenoid 245 and forward clutch control piston344 to control the engagement of the forward clutch. The controller canprovide an actuation current to the fourth electronic solenoid 245 toengage the forward clutch control piston 344, and can inhibit current tothe fourth electronic solenoid 245 to disengage the forward clutchcontrol piston 344.

Likewise, a fifth control passage may be implemented in conjunction witha fifth electronic solenoid 247 and reverse clutch control piston 346 tocontrol the engagement of the reverse clutch. The controller can providean actuation current to the fifth electronic solenoid 247 to engage thereverse clutch control piston 346, and can inhibit current to the fifthelectronic solenoid 247 to disengage the reverse clutch control piston346.

FIG. 4 is a simplified functional block diagram of an embodiment of anelectronic controller 108 for a variable ratio transmission. Thecontroller 108 can be, for example, the controller illustrated in FIG. 1and can be used, for example, to control the transmission of FIG. 3A.The electronic controller 108 functions are broken down into systeminputs, controller outputs, range control, variator control, torqueconverter clutch locking and diagnostics.

The controller 108 implements a strategy for controlling the range boxand variator. The controller 108 determines the appropriatefunctionality as a function of driver (user) and vehicle inputs in theshift point module 410. The shift logic module 430 determines theappropriate clutches to apply and their required torque capacity. Therate of apply and corresponding solenoid current are computed in theshift quality control module 450. The controller 108 also determineswhen use of the variator is enabled.

The controller 108 can also be configured to include diagnostics andfailure modes to enable the ability to avoid dangerous or destructiveconditions and to allow reduced functionality operation in case offailure when possible. Major electrical and hydraulic failures can beaddressed, as well as highly degraded performance.

The controller 108 includes a plurality of modules configured to receiveinput from one or more sensors or controls in the drive system. Eachexternal signal that enters the electronic controller can represent asensor measurement or a control state. Prior to using the inputinformation, the input data may undergo signal conditioning, scaling,error checking, and the like, or some combination thereof.

The input signals and control states may be analog signals, digitalsignals, or a combination of analog and digital signals. An initialcomplement of analog inputs for a particular implementation is listed inTable 1 as an illustrative example. A controller 108 need not supportthe entire complement of input types. For example, the first threeanalog signal types may be implemented within a production controller108. The others analog inputs may be supported in the productionimplementation or may be included for potential use in developmentunits.

TABLE 1 Analog Inputs Input Range Excitation Variable Units Range Typethrottle position 0-5 V 5 V throttle % 0-100  potentiometer sumptemperature 0-5 V 5 V Tsump deg. C. −50 . . . 200 thermistor variatortemperature 0-5 V 5 V Tcool deg. C. −50 . . . 200 thermistor P1 servopressure 0-5 V P1 kPa (gauge) 0-3400 transducer P2 servo pressure 0-5 VP2 kPa (gauge) 0-3400 transducer reverse clutch pressure 0-5 V Prev kPa(gauge) 0-3400 transducer forward clutch pressure 0-5 V Pfwd kPa (gauge)0-3400 transducer direct clutch pressure 0-5 V Pdir kPa (gauge) 0-3400transducer manual low clutch pressure 0-5 V Pmlow kPa (gauge) 0-3400transducer line pressure 0-5 V Pline kPa (gauge) 0-3400 transducer lubepressure 0-5 V Plube kPa (gauge) 0-3400 transducer servo position A +/−5V XservoA mm +/−15.5 transducer servo position B +/−5 V XservpB mm+/−15.5 transducer

The controller 108 may also be configured to accept one or more digitalinputs. In one embodiment, an active signal is pulled to ground. Thatis, the controller 108 provides a pull-up function.

The controller 108, and in particular the controller modules receivingsensor and state inputs, can be configured to condition or otherwiseprocess the received input signals. For example, the controller 108 canperform signal conditioning on the input signals to reduce or otherwisemitigate noise effects. For example, the controller 108 may conditioninputs that are provided by a thermistor. The controller 108 mayimplement a pull-up resistor at each thermistor input to form a voltagedivider, with the junction voltage providing an indication ofresistance.

Typically, the controller 108 performs a linear translation from inputvoltage to the engineering units, as indicated in Table 1. Inputs thatare scaled, shifted, or otherwise conditioned or processed, such asthermistor inputs, may be translated based on a calibration. A lookuptable can be used to perform this calibration. Predetermined inputsignal ranges can be used by the controller 108to check for sensorfailures. The detection of erroneous values will be flagged by thecontroller 108 for the diagnostic routines.

One or more values may be predetermined and stored within one or moremodules of the controller 108. For example, physical dimensions can beused as parameters to estimate variables that are not directly measured.In one instance, the parameters for a range box based on a particularRavigneaux gear set model are:

P1m=3.62 ratio nring/nsum1

P2m=2.77 ratio nring/nsum2

The radius of a particular implementation of the variator ball (planet)is:

Rballm=31.75e−5 m model variator ball radius

The plurality of modules operate on the sensors in conjunction with oneor more predetermined maps, algorithms, or processes implemented inmodules within the controller 108 to determine one or more controlsignals. One or more output control modules can operate to provide theone or more control signals to their respective control destinations.

The controller 108 outputs can be primarily solenoid controls to controlelectronic solenoids in the transmission. In addition, the controller108 can be configured to provide one or more pieces of diagnosticinformation. The controller 108 can be configured, for example, toprovide such diagnostic information as a driver warning light.

The electronic control of the transmission is achieved throughelectrohydraulic solenoids. A list of the solenoids and their generalcharacteristics is given in Table 2 as an illustrative example. Severaldifferent types of solenoid are employed. These may include avariable-force solenoid (VFS), a variable bleed solenoids (VBS), on/offshift solenoids and pulse-width modulated on/off solenoids (PWM). TheVFS and VBS types are typically used with closed-loop current control inorder to maintain accuracy of control. The on/off solenoids typicallyrequire no feedback.

TABLE 2 Solenoid Control Outputs Solenoid Feedback Voltage Current FreqVariable Units Range Default Line pressure VFS current 9-14 V   1 A 300Hz iLine mA 0-1000 press. Low VBS current 9-14 V   1 A 300 Hz iLow mA0-1000 press. Direct VBS current 9-14 V   1 A 300 Hz iDirect mA 0-1000exh. Reverse VBS current 9-14 V   1 A 300 Hz iReverse mA 0-1000 press.Ratio VBS current 9-14 V   1 A 300 Hz iRatio mA 0-1000 press. Forwardshift no 9-14 V   1 A  0 Hz ManShift logic 0-1   exh. Forward sequenceno 9-14 V   1 A  0 Hz FwdOn logic 0-1   exh. TCC PWM no 9-14 V 1.5 A  32Hz TCCduty % 0-100  exh.

The controller 108 can generate PWM signals, using, for example,microcomputer timers. Pulses are generated at the appropriate frequencywith width according to duty cycle. Narrow pulses represent low dutycycle and wide pulses for high duty cycle. Although they are notspecifically designated as PWM solenoids, the VFS and VBS can use a PWMsignal as part of their control. In this case, however, the appropriateoutput module from the controller 108 adjusts the duty cycle that anaverage current feedback tracks the command. The controller 108 cangenerate PWM signals with a relatively high frequency, that is typicallyhigher than an update rate of non-PWM controlled solenoids, and higherthan a response time of the solenoid, so that the solenoid valve doesnot actually cycle on and off each pulse, but instead, provides a smoothresponse. In effect, the response time characteristic of the electronicsolenoid operates as a lowpass filter to smooth the PWM signal.

The controller 108 includes a shift point module 410 configured toreceive input from one or more of a shift schedule module 412, aplurality of sensors, including, but not limited to, a vehicle speedsensor, a throttle position sensor, one or more control state sensors,such as a shift position lever state sensor, and the like.

The list of sensor signals and switch inputs in Table 3 represents thedigital inputs to the transmission controller 108. Table 3 is anillustrative example of one embodiment of the sensor signal and switchinputs.

TABLE 3 Digital Inputs Input Range Sense Variable Logic Type pressureswitch N 0-12 V ground PRNDLN code boolean pressure switch R 0-12 Vground PRNDLR code boolean pressure switch P 0-12 V ground PRNDLP codeboolean zero throttle switch 0-12 V ground throttle0 inverted boolean100% throttle switch 0-12 V ground throttle100 inverted boolean PRNDLPark Switch 0-12 V ground ParkSwitch inverted boolean PRNDL Manual+ 0-12V ground ManualUp inverted boolean PRNDL Manual− 0-12 V groundManualDown inverted boolean Brake 0-12 V ground BrakeSwitch invertedboolean Perf/Economy 0-12 V ground Performance TRUE boolean Switch

An embodiment of a pressure switch manifold decoding is shown in Table 4as an illustrative example. On each of the three input lines (N, R andP), logic 0 represents a closed switch and 1 is open, or floating.Because neutral and park are identical hydraulically, only two of thebits (N and P) are needed to identify the four possible states. Park andneutral can be distinguished via the park switch on the PRNDL lever. Thedecoded PRNDL position is represented by the variable lever.

TABLE 4 Pressure Manifold Logic Range N R P Lever Park 1 0 1 0 Reverse 00 1 1 Neutral 1 0 1 2 Drive 1 M 0 3 Low 0 M 0 4

In Drive and Low, the third pressure manifold bit, R, indicates thestatus of the manual low clutch. The table entry M is logic 1 when theclutch is pressurized and logic 0 when it is vented.

The five speed inputs listed in Table 5 can be sensed by the frequenciesof toothed wheels passing a magnetic pickup. Each speed sensor generatesa pulse train that triggers timer circuits, for example, within theshift point module 410 or an optional speed sensor conditioning module(not shown). The timers can determine the period of each pulse, and thereciprocal of the period is the frequency of the pulse train. Pulses ofa duration that is either much shorter or larger than the trend can beassumed to represent noise and can be discarded. Persistently erratic orlost pulses can be reported to a diagnostic routine.

In one embodiment, the frequency can be scaled. For example, the pulsefrequency can divided by the number of pulses per revolution and theresult multiplied by 60 to arrive at the shaft speed in rpm. Vehiclespeed can be approximated from tail shaft speed, neglecting slip, whichmay be negligible.

TABLE 5 Speed Inputs Input Pulse/Rev Type Voltage Variable Units RangeType Engine speed TBD Hall 5 V Ne rpm 0-10000 unsigned Turbine speed TBDHall 5 V Nturb rpm 0-10000 unsigned Variator output speed TBD Hall 5 VNvar rpm 0-10000 unsigned Reverse ring speed TBD Hall 5 V Nring rpm0-10000 unsigned Tail shaft speed TBD Hall 5 V Ntail rpm 0-10000unsigned

The shift point module 410 operates on the inputs to determine which oneof a plurality of ranges to operate within. The electronic controller108 configured to control the transmission of FIG. 3A having a two-ratiorange box and a CVT variator can implement virtually an infinite numberof ratio combinations within the ratio range. The controller 108, and inparticular, the shift point module 410 is configured to providetransmission control based on a predetermined number of control ranges.The number of ranges and the span for each of the predetermined controlranges can be stored, for example, in the shift schedule module 412. Forexample, the controller 108 can implement three control ranges. Theshift point module 410 can determine, based on the inputs, the relevantcontrol range and can identify the active control range by the variablengear. Table 6 is an example of an embodiment of transmission controlrange designations. In one example, the shift point module 410determines the appropriate range based on the shift curves stored in theshift schedule module 412.

TABLE 6 Transmission Control Range Designations ngear variator range 1Underdrive Low 2 Engine speed control Low 3 Overdrive Direct

The shift point module 410 can also determine and output a variator flagvalue. The shift point module 410 can determine the state of thevariator flag based at least in part on the ngear control range state.The shift point module 410 can output, for example, an active variatorflag in those control range states when active variator control isenabled.

In the first control range, the controller 108 controls both thevariator and range box to be in low, giving the maximum possibleunderdrive. In the second control range, the controller 108 controls thevariator ratio and the range of ratios can be shifted toward one-to-oneand beyond into overdrive, while the range box remains in low. In thethird control range, the controller 108 controls the range box to shiftto one-to-one (direct) with the variator controlled to operate in fulloverdrive.

The shift point module 410 provides the ngear value and appropriateshift flags to the shift logic module 430. The shift logic module 430operates on the input values and outputs shift control commands as wellas a line pressure valve control. For example, the shift logic module430 can determine the current state of the control range based on thengear value provided by the shift point module 410. The shift logicmodule 430 operates on an active upshift flag to command an upshift ofthe transmission. Conversely, the shift logic operates on an activedownshift flag to command a downshift of the transmission.

The shift logic module 430 can also be configured to command theapplication of the torque converter clutch to control whether the torqueconverter is engaged into a lockup state. The controller 108 can lockthe torque converter clutch in order to operate the transmission moreefficiently. The shift point module 410 in combination with the shiftlogic module 430 may determine the conditions for torque converterlockup in a manner similar to the range control strategy. The conditionsunder which the controller 108 applies the torque converter clutch canbe determined by driver input and vehicle speed. In one embodiment, theshift point module 410 can implement the conditions for torque converterlockup as another range value in the number of predetermined controlranges. In such an embodiment, the shift point module 410 can implementthe additional torque converter lockup clutch as an additional shiftstrategy stored in the shift schedule module 412.

The shift logic module 430 can be configured to provide line pressurevalve control information directly to a line pressure solenoid in orderto adjust the line pressure within the transmission. This is discussedin further detail below. The shift logic module 430 can also beconfigured to directly control the torque converter clutch solenoid toselectively engage or disengage the torque converter clutch.

The shift logic module 430 sends the shift commands, whether upshift ordownshift, to a shift quality control module 450 that operates tocontrol the appropriate pressure control solenoid to achieve aparticular shift quality. As will be subsequently explained in furtherdetail, the shift quality control module 450 can operate on the shiftcontrol from the shift logic module 430 by implementing a particularshift profile. The shift quality control module 450 implements aparticular shift profile, for example, by controlling current applied tothe appropriate shift solenoid based on the shift profile.

The shift quality control module 450 can implement different shiftprofiles to provide differing shift characteristics. For example, theshift quality control module 450 can implement a rapid first shiftprofile when the transmission is operated in a performance mode and canimplement a gentle second shift profile when the transmission isoperated in a luxury mode.

A variator mode module 420 operates to control the ratio provided by thevariator. The variator mode module 420 can determine when the variatorcan be controlled according to several different modes. Typically, theengine speed is controlled by the variator in order to achieveobjectives of performance or fuel economy, for example. Alternatively, aspecific ratio may be commanded. In each of these cases, the objectivecan be translated to a desired instantaneous engine (or turbine) speed.A variator valve can be adjusted dynamically to track this setpoint.Full overdrive and underdrive may be commanded at the extremes ofoperation.

The variator mode module 420 can be configured to receive sensor andcontrol state inputs which may be the same, distinct from, or at leastpartially overlap the sensor and control state inputs received at theshift point module 410. The variator mode module 420 also receives avariator flag value from the shift point module 410.

The controller 108, and in particular the variator mode module 420, maylimit dynamic control of the ratio of the variator to those situationswhere the variator flag is active. If the variator flag is active, thevariator mode module 420 can determine a variator mode and acorresponding variator control based on the various inputs.Alternatively, if the variator flag is inactive, the variator modemodule 420 determine a static state of the variator based on the inputsignals. In an alternate embodiment, the variator mode module 420 mayalso receive the ngear value from the shift point module 410 anddetermine the state of the variator control based in part on the ngearvalue as well as the state of the variator flag.

The variator mode module 420 can determine an active one of a pluralityof variator modes based on the input signals. The controller 108 can,for example, implement a plurality of variator modes. Although there isvirtually no limit to the number of variator modes that the controller108 may implement, the majority of driving conditions may be satisfiedusing fewer than approximately ten variator modes. Each variator modeallows the controller 108 to control the variator (or CVT) to providegood drivability according to the driver inputs, engine and vehicleconditions. Examples of the various variator modes and conditions fortheir operation are provided below.

The variator mode module 420 outputs the variator mode value to anengine speed setpoint module 440. The engine speed setpoint module 440operates to control the variator in order to control at least one of anengine speed or variator ratio that depends on the variator mode.

The engine speed setpoint module 440 can determine a desired enginespeed, for example, based in part on one or more algorithms, enginemaps, and the like or some combination thereof. The various engine mapsand algorithms can be stored within memory within the engine speedsetpoint module 440 or in memory otherwise accessible by the enginespeed setpoint module 440.

The engine speed setpoint module 440 provides the target engine speed toa closed loop algorithm control module 460. The closed loop algorithmcontrol module 460 receives the target engine speed and actual enginespeed as input values. The actual engine speed can be determined basedon one or more sensor values, such as, for example provided by acrankshaft sensor or flywheel sensor.

The engine speed setpoint module 440 generates a control output tomaintain the actual engine speed to within an error tolerance of thetarget engine speed. In one embodiment, the engine speed setpoint module440 outputs a current signal that is used to control a variator valve.In a particular example, the engine speed setpoint module 440 modulatesthe current provided to an electronic solenoid that controls a positionof a variator control piston within the variator.

The engine speed setpoint module 440 can, for example, compare thetarget engine speed against the actual engine speed and generate anerror signal that is used to control the output signal. The engine speedsetpoint module 440 can implement a loop filter and loop gain to achievethe desired control characteristics. For example, a lower bandwidth onthe loop filter may eliminate unwanted spurious effects on the controloutput, but at a cost of speed at which the engine speed setpoint module440 can react to sudden changes in either the target engine speed or theactual engine speed.

The engine speed setpoint module 440 can control the ratio solenoid ofthe variator so that the measured engine speed feedback tracks thesetpoint. The engine speed setpoint module 440 can perform PI(proportional+integral) control. The general form of the equations isshown below.

In proportional control, the difference between the setpoint andfeedback represents the closed loop error. This difference is multipliedby a constant of proportionality to increase or decrease the solenoidcurrent and corresponding variator ratio, as required.

e0=Neset−Ne

u0=Kvarp*e0,Kvarp=1e−4 A/rpm,proportional gain

The engine speed setpoint module 440 can accumulate the integral of theerror to minimize steady-state error in the control loop. The enginespeed setpoint module 440 can approximate this integral in discretetime.

e1=e1+Ts*e0,

uI=Kvari*e1,

Kvari=0 A/rpm/sec integral gain

Talg=0.01 sec sample time interval

The engine speed setpoint module 440 can limit the sum of the controlaction to be within a usable range of the solenoid. The engine speedsetpoint module 440 can perform ratio limit based on the pseudo codeprovided below.

  if (u0 + ul > iRatioMax) iRatio = iRatioMax freeze the value of e1else if (u0 + u 1 < iRatioMin) iRatio = iRatioMin freeze the value of elelse iRatio = u0 + u 1

The functions of the various modules within the controller 108 may beimplemented as hardware, software, or as a combination of hardware andsoftware. The controller 108 can include a processor 492 or computer andone or more processor readable or computer readable media. The one ormore processor readable or computer readable media can be implemented,for example, as memory 494. The processor readable or computer readablemedia can be encoded with one or more instructions, data, or informationthat are arranged as software instructions that, when executed by theprocessor or computer, implement the functionality of portions or all ofone or more of the modules within the controller 108.

FIG. 5 is a simplified diagram of an embodiment of a transmission shiftcurve 500 implemented by an electronic controller. As described above,the controller may implement three distinct ngear control ranges.

The appropriate range is determined by the controller according to shiftcurves such as those shown in FIG. 5. A threshold is calibrated, interms of vehicle speed as a function of throttle. V12 is the curve thatdirects the transmission to ngear=2. This enables the variator ratiocontrol as a function of engine speed. The V21 is the downshift curvefor the overall transmission into low. The curve varlow shows that thevariator will be in low ratio prior to the 2-1 downshift. Note that thetransition into low is at a somewhat lower speed to prevent hunting. V23is the curve that signals an upshift, ngear=3, to the range box. Thisshifts the range box from low to high, which may be direct. Thecontroller 108 commands the variator to a predetermined ratio, such as apredetermined overdrive ratio by virtue of the varhigh curve. The V32curve signals, ngear=2, the range box to downshift from direct to lowand enables the variator back into a control mode.

The shift curves can be implemented as table values stored in the shiftschedule module. The tables values and shift curves can be changed toachieve a particular vehicle performance criterion. For example, theshift schedule module can be configured to store a plurality of shiftcurves corresponding to a plurality of selectable user selectabletransmission characteristics. The controller can select or otherwiseaccess a particular shift curve instantiation based on the value of theuser selectable characteristic. In one example, a user interface maypermit a user to select from a performance mode or an economy mode. Adistinct shift curve may be stored within the shift schedule module foreach user selectable mode and accessed by the controller upon activationby the user. The various shift curves can be based on maximum enginetorque, and may differ based on the type and characteristics of theprime mover coupled to the transmission.

An illustrative example of the data included in a shift curve isprovided below.

Th_set = [0 10 20 40 60 90 91 100] pct throttle angle V12 = [12 12 12 2025 30 30 30] kph 1-2 upshift V21 = [10 10 10 10 10 10 10 10] kph 2-1downshift V23 = [45 45 60 80 100 125 130 130] kph 2-3 upshift V32 = [4242 50 73 92 120 125 125] kph 3-2 downshift Tconfirm sec delay time forshift point

The variator control described above can be implemented, for example,with five variator control modes listed in Table 7. These variatorcontrol modes permit the transmission to provide good drivabilityaccording to the driver inputs, engine and vehicle conditions.

TABLE 7 Variator Control Mode Definition Variator Mode Name Function 0Idle Underdrive 1 Launch Underdrive 2 Drive Engine Speed Control 3 HighOverdrive 4 Manual Ratio Control 5 Coast Ratio Control 6 Low FreewheelRatio Control 7 Reverse Ratio Control

FIG. 6 is a simplified diagram of an embodiment of an engine speed map600 implemented by an electronic controller. The variator control modescan be implemented directly be the variator mode module.

The variator mode module may implement the ratio control of modes 0, 1,and 3 directly based on a predetermined control value for the variatormode. In modes 0 and 1, the variator mode module can be configured toset the variator ratio to a predetermined underdrive value, such as aminimum underdrive ratio. Conversely, in mode 3, the variator modemodule can be configured to set the variator ratio to a predeterminedoverdrive value, such as a maximum overdrive ratio.

Mode 2 is the main dynamic control mode of the variator. The controlstrategy the for mode 2 implemented by the controller, and in particularthe variator mode module, can be to maintain the engine speed at someoptimum operating point based on a specific criteria. The ratio of thevariator is changed to satisfy a closed loop engine speed controlsystem. The engine speed set point function is based on the chosenoperating criteria. The criterion for this strategy is based on anengine speed set point established near the maximum engine torque foreach throttle. This performance criterion can be seen by plotting theengine set points on the engine map 600.

Th_setv = [0 10 20 40 60 90 100] pct throttle angle Ne_set2 = [1500 15001675 2450 rpm engine speed setpoint 3200 4200 4200] mode 2

FIG. 7 is a simplified diagram of an embodiment of a variator ratio map700 implemented by an electronic controller. The variator mode modulemay implement the variator ratio map 700 of FIG. 7 via one or more lookup tables for the corresponding modes. An example of the type ofinformation included in the look up tables is provided below. Thevariator mode module may map the predetermined ratio to a correspondingsolenoid control value.

V_set = [O 10 20 40 60 90 100 120] kph Vehicle speed mode 4, 5, 6Ratio_set4 = [1.88 1.88 .55 .55 .55 .55 variator ratio set point mode 4.55 .55] Ratio_set5 = [1.88 1.88 1.5 1.15 .75 variator ratio set pointmode .55 .55 .55] 5&6

FIG. 8 is a simplified diagram of an embodiment of a variator ratio map702 implemented by an electronic controller. In the embodiment of FIG.8, the variator ratio map is implemented in a look up table and is usedby the variator mode module to control the variator ratio in mode 7,corresponding to reverse. An example of the type of information includedin the look up tables is provided below. The variator mode module maymap the predetermined ratio to a corresponding solenoid control value.

V_set = [0 10 20 40 60 90 100 120] kph Vehicle speed set point mode 7Ratio_set7 = [100 100 100 100 100 55 variator ratio set point mode 7 5555]

FIG. 9 is a simplified diagram of an embodiment of an engine speed limitmap 900 implemented by an electronic controller. The electroniccontroller may implement an engine speed limit that is based on vehiclespeed in order to limit or otherwise prevent engine damage that mayoccur as a result of exceeding reasonable engine speed limits.

In the embodiment of FIG. 9, the engine speed limit map 900 isimplemented in a look up table and is used by the controller to controlthe engine speed, for example, by providing feedback to an enginecontrol module. An example of the type of information included in thelook up table is provided below.

Veh_limit = [20 40 60 80 100 120] kph Vehicle speed for Neset limitNeset_limit = [4000 4000 4000 5000 6000 6000] rpm Neset limit

Alternatively, the variator control modes indicated in Table 9 can beimplemented in each case entirely with engine speed control. That is,although other operating objectives may indicated, such as underdrive,overdrive, or ratio control, those objectives can generally betranslated to a desired engine speed in each case. In modes zero, one,and three, out-of-range speeds can be used to force the controls tosaturate towards one of the ratio extremes. For modes four throughseven, the variator output speed and desired ratio are used to computethe corresponding engine speed. The desired ratio is calibrated as afunction of vehicle speed in these cases. The computed engine speed setpoint can be filtered with a first-order filter in order to preventcontrol activity that is too abrupt.

${Neset} = \left\{ \begin{matrix}7000 & {Idle} \\{f\left( {{throttle},{veh\_ speed}} \right)} & {Drive} \\500 & {Transmission} \\{{g_{1}({veh\_ speed})}*N\mspace{14mu}{var}} & {Coast} \\{{g_{2}({veh\_ speed})}*N\mspace{14mu}{var}} & {\ {Manual}}\end{matrix} \right.$

FIG. 10 is a simplified diagram of an embodiment of a variator ratelimit map 902 implemented by an electronic controller. Limiting may alsobe applied to restrict the rate of ratio change in the downshiftdirection. The limit values of the ratio valve current (iRatioMax andiRatioMin) can be a function of vehicle speed. The rate limit map may beimplemented as a look up table. An example of the type of data in thelook up table is provided below.

iRat0 = 0.7 A null current V_limit = [10 20 40 60 80 100 120] kphvehicle speed for variator valve limit iRsol_limitset = [1 .85 .8 .78.75 A current limit .75 .75]

FIG. 11 is a simplified diagram 904 mapping estimated engine torque tothrottle position. The engine torque map may be predetermined forparticular type of prime mover coupled to the transmission. The enginetorque map may be stored as a lookup table in memory. The controller 108can estimate engine torque as a function of throttle. Clutch capacityrequirements are computed as a function of engine torque.

The controller can implement transmission range selection according tothe logic of Table 8, which may be implemented in the shift logicillustrated in FIG. 4.

TABLE 8 Shift Control Logic Clutch Capacity Manual Variator OperatingMode Reverse Forward Direct Low Control Park Underdrive Reverse TfCRUnderdrive Neutral Hold Drive ngear = 1 TfCL Underdrive ngear = 2 TfCLEnable ngear = 3 TfCL TfCH Overdrive Low ngear = 1 TfCL TfCL Underdrivengear = 2 TfCL TfCL Enable

TABLE 9 Solenoid Control Logic Solenoid Excitation Operating Mode SHIFTSEQ REV LOW DIR RATIO Park 0 0 1 1 0 1 Reverse 0 0 0 1 0 1 Neutral 0 0 11 0 C Drive ngear = 1 0 0 1 0 0 1 ngear = 2 0 0 1 0 0 C ngear = 3 0 0 10 1 0 Low ngear = 1 1 1 1 0 0 1 ngear = 2 1 1 1 0 0 C

The controller can, for example, implement the modes in the shiftcontrol logic of Table 8 using the following pseudocode, where theparameters Vrev and Vmanlow are constants that represent vehicle speedthresholds, above which the controller inhibits the corresponding shift.

if lever is in Park or Neutral  release all clutches if lever is shiftedto Reverse  if Vkph ≤ Vrev   apply Reverse clutch  else   inhibitreverse range until Vkph ≤ Vrev, then apply clutch if lever is shiftedto Drive  from Park, Reverse or Neutral (with ngear < 3)   apply Forwardclutch  from Low   keep Forward clutch locked and release Manual Lowclutch  from Neutral with ngear = 3   apply Direct clutch, then lockForward clutch if lever is shifted to Low  from Park or Reverse   applyManual Low clutch, then lock Forward clutch  from Drive or Neutral   ifVkph > VmanLow    inhibit shift   else if powered with one-way holding   lock Manual Low clutch and keep Forward clutch locked   else    applyManual Low clutch, then lock Forward clutch if lever is in Drive  if anupshift to ngear = 3 is detected   apply Direct clutch to shift offone-way (Forward clutch locked)  if a downshift to ngear < 3 is detected  release Direct clutch and keep Forward locked so one-way holds

The controller can determine the application of the various clutchesbased on the shift control logic and can implement the logic byselectively enabling or disabling current applied to control solenoids.For example, the controller can implement the logic of Table 8 bysetting the solenoid outputs according to the control shown in Table 9.The values indicated in the table represent electrical state, with zerofor off and one for on. For the modulated solenoids (reverse, low anddirect) the value indicates a steady-state value. In the case of theratio solenoid, the letter C indicates that the solenoid is controlledto achieve the speed or ratio objective described in the portiondescribing variator control.

As described above in relation to the fluid flow diagram of FIG. 3C, thefluid line pressure provided by the pump may be dynamically regulated orotherwise dynamically controlled by the controller to enable particulartransmission performance in each of the various operating modes.

FIG. 12 is a simplified diagram of an embodiment of a line pressureschedule 906. The line controller can dynamically regulate the linepressure to a plurality of levels that can map to the varioustransmission operating modes. As shown in the line pressure schedule 906of FIG. 12, the controller can control a solenoid or other pressureregulator to achieve three distinct line pressures. A first lowest linepressure can be implemented when the transmission is selected to be inneutral or park. A second intermediate line pressure can be used whenthe transmission is selected to be in drive or low. A third highest linepressure can be sued when the transmission is selected to be in reverse.Examples of the values for the line pressures are provided below.

Plinemin = 6.8e5 n/m{circumflex over ( )}2 min line pressure LineSF =1.25 safety factor for minimum line pressure PlineSetMin = 8.5e5n/m{circumflex over ( )}2 lowest setpoint PlineSetNom = 13.6e5n/m{circumflex over ( )}2 nominal line pressure PlineSetMax = 22e5n/m{circumflex over ( )}2 maximum line pressure for high torque reversepLinemset = le5*[6 8 10 12 14 16 18 20 221] llinem = [1 0.78 0.7 0.630.55 0.47 0.37 0.2 0] A solenoid valve current amps

FIG. 13 is a simplified diagram of an embodiment of a line pressurecontrol map 908. The line pressure control map 908 can be used tocalibrate an electronic solenoid used to control the line pressure. Inone embodiment, portions of the map may be stored in memory as a lookuptable and accessed by the controller to set the line pressure based onthe schedule of FIG. 12. Alternatively, only those informationcorresponding to the desired line pressures in the line pressureschedule of FIG. 12 may be stored in memory for access by thecontroller.

FIG. 14 is a simplified diagram of an embodiment of a clutch applicationprofile 1402.

The shift quality of an automatic range transmission requires control ofthe driveline dynamics during the engagement and disengagement ofclutches during gear ratio changes. The main performance criteria are asmooth shift with good clutch durability. Shift quality of a shift isbased on the application of hydraulic pressure to the clutch in bothamplitude and timing. This control system has several parameters thatcan be adjusted to modulate the hydraulic pressure and therefore theresultant clutch torque.

The clutch apply torque set point profile 1402, as shown in FIG. 14, isbased on a number of calibration parameters. The required clutch torquemust balance the static input torque to the range box in addition todynamic torque required to synchronize the clutch. As an example, for anupshift the torque clutch set point is based on the followingparameters:

Tfc=Kcratio*Tinest+Kcratio 1e*(Ne0−Ne1)/tshift

-   -   Where:    -   Kcratio=torque ratio clutch to input    -   le=engine inertia    -   Ne=engine speed    -   Tshift=shift time

In order to simplify the shift quality calibration the required clutchsetpoint uses a step input based on a single coefficient and anestimated range box input torque. A low rate torque ramp can be used forfine-tuning.

Note that, in addition to the value of the step, TfCH, defined in FIG.14, there are three calibration parameters associated with theapplication.

dTfCH=slope of torque ramp, Nm/sec

TdoneCH=duration of ramp, sec

TfCHmax=maximum torque for lockup

The examples provided are applicable for control of the direct clutch inthe transmission of FIG. 2. Similar parameters can also be defined forthe reverse and low clutches.

The main parameter used for shift quality calibration is the stepcoefficient Kcxx. The larger the coefficient value, the shorter theshift. A shorter shift causes a greater driveline disturbance.

Forward clutch/manual TfCLmax = 540 nm max torque Kcls310 = 2.0 nm/nmdrive 1st gear Kclp400 = 1.15 nm/nm manual low dTfCL = 10 nm/sec torqueramp TdoneCL = 2.0 sec timer for max torque series Tmandone = 2.0 sectimer for max torque manual Reverse clutch TfCRmax = 1600 nm max torqueKcrl00 = 8 nm/nm Kcrl01 = 16 nm/nm dTfCR = 200 nm/sec TdoneCR = 5 Directclutch TfCHmax = 400 Kch330 = 0.45 dTfCH = 20 TdoneCH = 5

The hydraulic pressure needed to engage the clutch is based on therequired clutch torque and clutch characteristics. FIG. 15 is asimplified diagram of an embodiment of a clutch pressure control map1404. The controller, and in particular the shift quality controlmodule, can store one or more clutch pressure control map 1404 as a lookup table in memory. The shift quality control module can access theclutch pressure control map to implement the shift quality as providedin the clutch apply torque set point profile of FIG. 14.

Although the controller can control the operation of the lockup clutchin the torque converter as an additional control range, the engagementand disengagement of the torque converter lockup clutch need not becontrolled to the same extent as, for example, the direct clutch used toengage the ranges of the range box. The controller typically applies thelockup clutch in conditions where the torque converter is operating near100% efficiency, and thus, the transition to a lockup condition does notresult in as great a transition as occurs when shifting the rangeprovided by the range box.

FIG. 16 is a simplified diagram of an embodiment of a torque converterclutch curve 1602. The controller applies the torque converter clutchaccording to logic that is similar to the control range selectiondescribed above. The controller can lock the torque converter clutch atlow speed with light throttle for efficiency. As the driver steps intothe throttle as sensed by the percentage of the throttle positionsensor, the controller unlocks the clutch to allow the converter tomultiply torque.

Torque converter lockup can be inhibited at low oil temperature in orderto allow losses in the fluid coupling to heat the oil. Furthermore, theconverter can remain locked at excessive temperature in order to preventthe generation of further heat.

The torque converter clutch control strategy is based on the criteria ofminimum operation in the unlocked open converter phase. The conditionsfor open converter are to provide good launch and enhance shift quality.The controller can store the parameters of the torque converter clutchcurve in memory. An example of stored parameters is provided below.

Th_settcc = [0 10 20 40 60 90 91 100] pct throttle angle VTClock = [1414 18 28 34 44 44 44] kph Torque converter lock up VTCunlock = [12 12 1212 22 34 34 34] kph Torque converter unlock

A controller can thus be configured according to the various embodimentsand features described herein to control a transmission, and inparticular, a transmission having at least one substantiallycontinuously variable ratio portion, such as a variator, CVT or IVT. Theexamples described above use an example transmission having a variatorin combination with a two-speed range box. In the process of controllingthe transmission, the controller executes various strategies andprocesses that permit transmission operation to be optimized overvarious conditions and corresponding criteria.

FIG. 17 is a simplified flow chart of an embodiment of a method 1700 ofcontrolling a variable ratio transmission. The method 1700 can beimplemented, for example, within the controller of FIG. 4 to control thevariable ratio transmission of FIGS. 2 and 3A.

The method 1700 begins at block 1710 where the controller, for exampleat the shift point module and the variator mode module, receives inputsignals that can include sensor values as well as control input values.

The controller proceeds to block 1712 and determines the active controlrange based on the input values. For example, the shift point module candetermine an active control range from a plurality of control ranges.Each of the control ranges can correspond to a range of transmissionratios. Two or more of the control ranges may include overlappingratios.

The controller proceeds to block 1714 and the variator mode moduledetermines the active variator mode from a plurality of variator modes.The variator mode module can determine the variator mode based on theinput values as well as the active control range or a signal, such asthe variator flag, that may be based on the active control range.

The controller proceeds to block 1716 and determines a range boxconfiguration, which can include a range box clutch engagementconfiguration, a range box ratio, and the like, or some combinationthereof.

The controller proceeds to block 1718 and determines the state of atorque converter clutch that can be based on the input signals and theactive control range. The controller proceeds to block 1720 andconfigures the variator based on the mode and input values. Thecontroller proceeds to block 1722 and configures the range box based onits determined configuration. The controller proceeds to block 1724 andconfigures the torque converter clutch based on whether the controllerdetermines it should be engaged or disengaged.

FIG. 18 is a simplified flowchart of an embodiment of a method 1750 ofcontrolling a variator in a variable ratio transmission. The method 1750can be implemented, for example, by the controller of FIG. 4 operatingon the transmission of FIGS. 3A-3C.

The method 1750 begins at block 1752 where the controller, for exampleat the shift point module and the variator mode module, receives inputsignals that can include sensor values as well as control input values.

The controller proceeds to block 1754 where the shift point module candetermine a variator mode based on the inputs. The controller proceedsto block 1756, where the shift point module determines an active controlrange The controller proceeds to block 1758 where the controller, forexample, using the shift point module, determines a range box ratiobased on the control range, the input signals, and a shift schedulestored in and accessed from the shift schedule module.

The controller proceeds to block 1760 where the variator mode module candetermine a desired variator ratio, for example, based in part on thevariator mode. The controller proceeds to block 1762 and the enginespeed setpoint module maps the ratio to a target engine speed.

The controller proceeds to block 1764 and controls the variator toachieve the target engine speed. The controller can, for example,utilize a closed loop control module to monitor an engine speed andcontrol a solenoid that controls a position of a longitudinal axis of arotating planet within the variator in order to achieve the targetengine speed.

FIG. 19 is a schematic diagram of an embodiment of a fluid flow diagramof an embodiment of a valve system 2500 that can be implemented on avariable ratio transmission such as the transmission 101. The associatedhardware represented by the symbols and schematic notations illustratedin FIG. 19 should be readily apparent to those having ordinary skill inthe relevant technology. The valve system 2500 can include a pump valvesubsystem 2502 configured to be in fluid communication with a number ofpressure control valves. In one embodiment, the pump valve subsystem2502 is adapted to cooperate with a pump 806 (FIG. 3A) provided on thetransmission 101. The pump valve subsystem 2502 can include a pressureregulator valve 2504. The pressure regulator valve 2504 controls, amongother things, the system pressure of the valve system 2500 (sometimesreferred to here as “line pressure”). The pressure regulator valve 2504is in fluid communication with a number of torque converter controlvalves 2506A, 2506B, 2506C. The torque converter control valves 2506 areadapted to control the engagement and disengagement of the torqueconverter 210, for example, among other things.

In one embodiment, the valve system 2500 includes a manual valve 2508 influid communication with the pressure regulator valve 2504. The manualvalve 2508 can be operably coupled to the PRNDL lever. The manual valve2508 is adapted to cooperate with, for example, the pressure switchmanifold described in reference to Table 4. In one embodiment, the rangebox 1600 consists of hydraulic friction clutches in communication withthe valve system 1500 that govern the engagement and disengagement ofeach clutch as governed by the control logic. FIG. 19 illustrates thehydraulic connection for each clutch in the range box. A reverse clutch2510, a forward clutch 2512, a direct clutch 2514, and a manual lowclutch 2516 are all engaged and disengaged by hydraulic pressure actingon the face of the clutch. The aforementioned clutches can besubstantially similar to the clutches included in the range box 1600.The passage of pressurized fluid to each clutch is achieved throughholes in the transmission case, for example, and ports in the valvesystem 2500. The valve system 2500 can include a set of reverse clutchcontrol valves 2518A and 2518B in fluid communication with the reverseclutch 2510. The valve system 2500 can include a direct clutch controlvalve 2520 in fluid communication with the direct clutch 2514. The valvesystem 2500 can include a forward clutch control valve 2522 in fluidcommunication with the forward clutch 2512. The valve system 2500 caninclude a manual low clutch control valve 2524 in fluid communicationwith the manual low clutch 2516. The manual low clutch control valve2524 is configured to be in fluid communication with the forward clutchcontrol valve 2522. In one embodiment, the valve system 2500 includes aclutch regulator valve 2526 configured to regulator pressure supplied tothe manual low clutch control valve 2524. Each of the control valves canbe adapted to cooperate with electrohydraulic solenoids as indicated inTable 2, for example.

In one embodiment, the manual valve 2508 is used to direct line pressureto the appropriate collection of valves for range box control. When “P”or “N” is selected, the manual valve moves to a position that blocksline pressure to all clutch control valves. When “R” is selected, themanual valve moves to a position that directs line pressure to thereverse clutch control valves 2518. The selection of “D” or “L” movesthe manual valve to a position that directs line pressure to controlvalves for the direct clutch 2514, the forward clutch 2512, and themanual low clutch 2516.

In one embodiment, the selection of “D” or “L” enables the coordinationof the direct clutch 2514, the forward clutch 2512, and the manual lowclutch 2516 as governed by the control logic. The forward clutch 2512and the manual low clutch 2516 are controlled with the forward clutchcontrol valve 2522 (“Fwd Sequence Valve” in FIG. 19), the manual lowclutch control valve 2524 (“Fwd/Man Shift Valve” in FIG. 19), and theclutch regulator valve 2526 (“Fwd/Man (Low) Reg Valve” in FIG. 19). Theforward clutch control valve 2522 and the low clutch control valve 2524are directional control valves in communication with normally exhaustedOn/Off solenoids.

In one embodiment, the selection of “R” moves the manual valve to aposition that directs line pressure to the reverse clutch control valves1518. The reverse clutch control valves can include two pressureregulators valves, a passive valve 2518B and an active valve 2518A. Theactive valve 2518A (“Reverse Reg Valve” in FIG. 19) is in communicationwith the control system through a normally pressurized variable bleedsolenoid. The regulated pressure is directed from the active valve 2518Ato the reverse clutch 2510 and to the passive valve 2518B (“reverseboost valve” in FIG. 19). The reverse clutch pressure is exhausted whenthe manual valve selection is changed from “R” and the control logiccoordinates the appropriate solenoid commands.

In one embodiment the valve system 2500 includes a lube pressureregulator 2528 configured to be in communication with the line pressureand a lubrication system of the transmission 101, for example. Lubesystem pressure is regulated either with a passive pressure regulator oractively controlled with a solenoid in the same manner as the mainpressure regulator. The valve system 2500 can include a solenoidpressure regulator 2530 configured to be in fluid communication with theline pressure. The solenoid pressure regulator 2530 supplies pressurizedfluid to a number of solenoids in the valve system 2500. In oneembodiment, the valve system 2500 includes a torque converter regulatorvalve 2531 configured to be in fluid communication with the torqueconverter control valves 2506. The valve system 2500 includes a ratiocontrol valve 2532 configured to cooperate with the variator 1200, forexample. In one embodiment, the ratio control valve 2532 is anopen-center pressure control valve.

The controller is not limited to controlling the transmission, but canalso serve to provide diagnostic information based on the various inputsignals provided to the controller. The controller can be configured tocontrol the transmission when detecting failure modes to preventcatastrophic failure of the transmission and to permit limited operationin failure modes.

Electrical failures can be broken down into two categories: loss ofpower and controller crash. A reasonable recovery of operation, perhapswith reduced function, is typically possible in both cases.

In the case of complete loss of electric power, all solenoids willoperate with zero current. The internal pressures controlled by thesolenoids will revert to default pressure states. The hydraulic systemwithin the transmission can be designed so that this represents a usable“limp home” mode. The variator can default to full overdrive and thetorque converter can default to an unlocked condition. The range boxstate can depend on the PRNDL position, and can operate, for example, inunder driver control. In Drive the default range is Low and in Reverse,Reverse. This facilitates vehicle launch and driving at reasonablespeed. Furthermore, if the failure occurs at high vehicle speed, theone-way clutch can overrun to prevent excessive engine speed.

Although the controller circuits are designed to be highly robust, theremote chance of loss of control can be addressed with a watchdog timer.This is an internal circuit that requires periodic timer resets duringnormal operation. If the controller program hangs up and doesn't performthe reset within the prescribed interval, the timer resets thecontroller system. This allows the controller to come back on line andmaintain control of the system.

Two general classes of hydraulic failure modes may be addressed. Theseclasses include loss of pressure and excessive backpressure.

Unexpectedly low pressure can be detected in two ways. The controllercan directly measure or otherwise receive signals indicative of varioussystem pressure levels and can compared the values to expected ranges.Even without the direct measurement of pressure, loss of pressure maylead to excessive clutch slip as indicated by speed inputs. In eithercase, excessive clutch slip will deteriorate friction plates and lowvariator pressure will lead to loss of control.

The prescribed countermeasure for this condition is to place thetransmission in neutral by releasing all clutches. This removes all loadfrom the friction plates and the variator. Although the vehicle can notbe driven in this condition, potentially destructive component wear isprevented. An indication to the driver of transmission failure may alsobe given.

The controller can measure or otherwise monitor the lube pressure aninput variable. In the event that lube pressure is lost or unexpectedlylow, a destructive situation is imminent. In this case the transmissionwill immediately shift to neutral so that no components will need tocarry power. The controller can illuminate the diagnostic lamp.

If a clutch pack is released but residual pressure is trapped,undesirable clutch drag will result. Again, this can be detected viamonitoring pressure or speed. The safest response to this condition isto alert the driver to stop the vehicle.

Two temperature sensors may be implemented in the controller system. Thefirst monitors the sump oil to indicate the mean fluid temperature. Thesecond is located in the variator to sense the temperature of thetraction fluid splashing on the ball (planet) contact patches.

Temperature extremes in the variator coolant are a sign of impendingcatastrophic failure. If this condition is detected the transmissionwill be immediately placed in neutral by releasing all clutches. Thisunloads the variator and minimizes any further potentially destructivecontact patch slip power. Although the vehicle cannot be driven, failingto this condition is the safest compromise and prevents further wear.

Low fluid temperature increases viscosity, restricting flow in somecircuits. This is not considered to be a failure but it can potentiallycompromise performance. Below a calibrated threshold, the control systemcan heat the oil to a reasonable working temperature by preventingtorque converter clutch lockup.

High fluid temperature can accelerate degradation of friction andtraction properties. Above a calibrated threshold, the converter of amoving vehicle can be controlled to always run locked in order to reducefurther heating. If the temperature continues to rise a warning lightwill alert the driver.

System speed measurements allow the computation of slip across eachfriction clutch. If slip is detected in cases where the clutch is knownto be applied with a high safety factor, it will be judged that thefriction material has degraded substantially. The driver will be alertedto the error and the clutch will be opened to prevent further damage andexcessive heating.

An input can be provided to the controller to measure the variator servoposition. The ring contact radii can be computed from this information,hence the mechanical ratio of the ball variator. This can be compared tothe speed ratio in order to determine the slip at the ring contactpatches. If the slip is determined to be above a calibrated thresholdthe variator is unloaded to prevent potential damage. As in the case ofhigh variator lube temperature, this is achieved by shifting thetransmission to neutral, resulting in a loss of vehicle power.

As used herein, the term coupled or connected is used to mean anindirect coupling as well as a direct coupling or connection. Where twoor more blocks, modules, devices, or apparatus are coupled, there may beone or more intervening blocks between the two coupled blocks.

The various illustrative logical blocks, modules, controller, andcircuits described in connection with the embodiments disclosed hereinmay be implemented or performed with a general purpose processor, adigital signal processor (DSP), a Reduced Instruction Set Computer(RISC) processor, an application specific integrated circuit (ASIC), afield programmable gate array (FPGA) or other programmable logic device,discrete gate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.A general purpose processor may be a microprocessor, but in thealternative, the processor may be any processor, controller,microcontroller, or state machine.

A controller or processor may also be implemented as a combination ofcomputing devices, for example, a combination of a DSP and amicroprocessor, a plurality of microprocessors, one or moremicroprocessors in conjunction with a DSP core, or any other suchconfiguration.

The steps of a method, process, or algorithm described in connectionwith the embodiments disclosed herein may be embodied directly inhardware, in a software module as one or more programmable instructionsto be executed by a processor, data, or information encoded onto aprocessor or computer readable media and executed by a processor orcomputer, or in a combination of the two.

The various steps or acts in a method or process may be performed in theorder shown, or may be performed in another order. Additionally, one ormore process or method steps may be omitted or one or more process ormethod steps may be added to the methods and processes. An additionalstep, block, or action may be added in the beginning, end, orintervening existing elements of the methods and processes.

The above description of the disclosed embodiments is provided to enableany person of ordinary skill in the art to make or use the disclosure.Various modifications to these embodiments will be readily apparent tothose of ordinary skill in the art, and the generic principles definedherein may be applied to other embodiments without departing from thespirit or scope of the disclosure. Thus, the disclosure is not intendedto be limited to the embodiments shown herein but is to be accorded thewidest scope consistent with the principles and novel features disclosedherein.

What is claimed is:
 1. A method of controlling a variable ratiotransmission in a drivetrain having a ball planetary type variator, thedrivetrain having at least two forward modes, a reverse mode, and one ofa neutral mode and a park mode, the method comprising: storing, in ashift schedule module, a shift schedule map; receiving, by a shift pointmodule, a plurality of input signals, wherein the plurality of inputsignals includes an engine parameter and a transmission ratio;determining an active control range from a plurality of control rangesbased at least in part on the plurality of input signals and the shiftschedule map, wherein each control range corresponds to a range oftransmission ratios; configuring a range box into one of the at leasttwo forward modes, the reverse mode, and the neutral mode or the parkmode; determining an active variator mode from a plurality of variatormodes based on the plurality of input signals and the active controlrange; and controlling an operation of the variator based on the inputsignals and the active variator mode.
 2. The method of claim 1, furthercomprising controlling actuation of a clutch to activate theconfiguration of the range box.
 3. The method of claim 1, furthercomprising controlling the range box to provide a gear ratio based onthe configuration of the range box.
 4. The method of claim 1, furthercomprising: determining a configuration of a torque converter clutchcorresponding to a torque converter that couples power from a primemover to the variator; and selectively engaging the torque converterclutch based on the configuration of the torque converter clutch.
 5. Themethod of claim 1, wherein receiving the plurality of input signalscomprises receiving at least one sensor value and at least one controlstate.
 6. The method of claim 1, wherein receiving the plurality ofinput signals comprises receiving a throttle position sensor input valueand a gear selector value.
 7. The method of claim 1, wherein determiningthe active control range comprises: retrieving at least a portion of ashift curve; and determining the active control range based on theportion of the shift curve and the plurality of input signals.
 8. Themethod of claim 7, wherein the plurality of input signals comprises: athrottle position sensor value; and a vehicle speed value.
 9. The methodof claim 1, wherein controlling the operation of the variator comprisesmodulating a current applied to an electronic solenoid to control aratio of the variator.
 10. The method of claim 1, wherein controllingthe operation of the variator comprises controlling the variator toprovide a ratio from a range of ratios that spans an underdrive ratioand an overdrive ratio.
 11. The method of claim 1, wherein controllingthe operation of the variator comprises controlling a longitudinal axisof a rotating planet within the variator.
 12. The method of claim 11,wherein controlling the longitudinal axis comprises controlling aposition of a shift lever coupled to the rotating planet by modulating acurrent applied to a control solenoid.
 13. A controller system forcontrolling a variable ration transmission in a drivetrain having a ballplanetary type variator, the drivetrain having at least two forwardmodes, a reverse mode, and one of a neutral mode and a park mode, thecontroller system comprising: a controller including a plurality ofmodules comprising: a shift schedule module configured to store a shiftschedule map on a computer readable medium; a shift point modulecommunicatively coupled to the shift schedule module and the computerreadable medium, the shift point module configured to: receive aplurality of electronic input signals from one or more sensors, whereinthe plurality of electronic input signals includes an engine parameterand a transmission ratio, determine an active control range from aplurality of control ranges based at least in part on the plurality ofelectronic input signals and the shift schedule map, and wherein eachcontrol range corresponds to a range of transmission ratios, andconfigure a range box into one of the at least two forward modes, thereverse mode, and the neutral mode or the park mode; a variator modemodule configured to receive the plurality of electronic input signalsand the active control range and determine a variator mode based on theplurality of electronic input signals and the active control range; anda control module configured to control a ratio of a variator based onthe variator mode, wherein each of the shift schedule module, the shiftpoint module, the variator mode module, and the control module areembodied on one or more of an application specific integrated circuit,at least one processor circuit, or software stored on a computerreadable medium and configured to be executed by a processor.
 14. Thecontroller system of claim 13, wherein the controller further comprisesa shift logic module communicatively coupled to the shift point moduleand configured to receive the active control range from the shift pointmodule, wherein the shift point module is configured to determine astate of an upshift flag and a downshift flag based on the plurality ofelectronic input signals, and wherein the shift logic module isconfigured to control engagement of at least one clutch controlling aratio of the range box coupled to the variator.
 15. The controllersystem of claim 14, wherein the controller further comprises a shiftquality control module coupled to the shift logic module and configuredto control an electronic solenoid to control engagement of the at leastone clutch, wherein the shift quality control module is configured todetermine an application rate and a corresponding solenoid current. 16.The controller system of claim 13, wherein the controller furthercomprises an engine speed setpoint module communicatively coupled to thevariator mode module and configured to determine an engine speedsetpoint value based on the variator mode, and wherein the controlmodule is configured to receive an engine speed value and is configuredto control the ratio of the variator based on the engine speed value andthe engine speed setpoint.